Browsing Tag: serotonin

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video. One summer afternoon when Doctor Martin Blaser
was still a medical student, he went to see an eleven-year-old boy who had suddenly become
ill and was hospitalized. He was perfectly fine until two days earlier when he suddenly
developed a fever and an upset stomach. The next day the fever worsened, and on the third
day, the boy developed small purplish dots on his body. The emergency room doctors quickly
realized the boy had Rocky Mountain spotted fever, something caused by a bite from a tick
infected with a type of bacteria called rickettsia. This bacterium multiplies within cells lining
blood vessels, invoking an aggressive immune response. Since this involves the brain’s
blood vessels, it caused a form of encephalitis, a swelling of the brain provoking a massive
headache. When Blaser accompanied doctors to see the
boy, the room was darkened as the light hurt his eyes, his body was covered with purple
spots, and he was thrashing around in his bed covered in sweat. He was yelling incoherently
as loud as he could while hallucinating. As Dr. Blaser explains in his book “Missing
Microbes,” the boy was started on an antibiotic called tetracycline and after just five days,
he was discharged from the hospital. Especially considering the Gut Microbiome
is the big topic in health and science recently, you may know that not all microbes are bad.
While there are pathogenic microbes like these just mentioned, at all times there are 500
to 1000 different species of bacteria in the human body. And the importance of their function
is becoming more apparent as we learn new things about them. However, it’s hard to picture how tiny microbes
in our gut contribute to our day to day cognition and brain function. In the case of rocky mountain
spotted fever it may not be surprising that the introduction of a deadly pathogen could
induce drastic changes in a person’s mental state. However, the relationship between the
microbes normally residing in the gut and how our brain operates becomes apparent when
we take them out. Scientists observing microbe-free mice living
in sterile bubbles quickly noticed that these mice have a personality that is distinct from
mice with gut microbes. Microbe-free mice were found to be more prone to taking risks
and they freely explore their environment. Risk taking might be good if you’re a young
entrepreneur, but the kind of risk these mice engage in is wandering further out in an open
field. For a mouse, this is an excellent strategy for quickly getting killed by a predator.
Not only are the mice unusually reckless, scientists also noticed that these microbe-free
mice have memory-related defects. The book “The Good Gut” by Erica and Justin
Sonnenburg describes how a group of researchers put normal and microbe free mice through some
memory tests. First, the mice were given five minutes to explore two new objects, a small
smooth ring and a large checkered ring. Then the objects were removed for twenty minutes.
After that, the large checkered ring and a new object, a star-shaped cookie cutter, were
put in the cages. Predictably, the mice with the normal microbiota checked out the cookie
cutter and paid less attention to the checkered ring because they already knew what it was.
The microbiota free mice, explored the new cookie cutter, but spent just as much time
checking out the old object – the checkered ring. It seemed that these mice had completely
forgotten an object they had just seen twenty minutes earlier. The forgetfulness in these mice may be explained
by the fact that the microbe free mice have lower levels of BDNF. BDNF, brain-derived
neurotrophic factor is a powerful protein important for learning and memory. It stimulates
the production of new brain cells and strengthens existing ones. Low levels of BDNF are linked
to depression and anxiety. Since making microbe-free humans would be
quite unethical, such experiments haven’t been repeated in humans, but… you may have
heard of the woman who, after receiving a fecal microbiota transplant, became obese.
The fecal microbiota transplant or FMT is just as it sounds, it’s taking the poop
from one healthy person and putting it into another person, in order to share the healthy
microbiota of the donor. FMT is not a common practice, but it’s the most effective treatment
for a Clostridium difficile infection, which causes diarrhea and abdominal pain for weeks.
In this case, the woman’s donor was her 16 year old overweight but otherwise healthy
daughter. The transplant went smoothly and successfully cured the woman’s issues. But,
over a period 16 months, the woman gained 34 pounds. And this happened despite persistent
diet and exercise efforts. She even went on a medically supervised liquid protein diet
and still could not get the weight off. On the flipside of this, it’s been found
that putting the microbiota of lean mice into other mice protects them from gaining weight.
So it looks like a microbiota transplant can transplant body types, but what about personality? In 2011, a research group at McMaster University
did an experiment with two different types of lab mice. One type had a personality that
was the mouse equivalent of anxious and the other type was sociable and extroverted. To
set a metric for how nervous the mice were, they put them on an elevated platform and
recorded how long it took for them to step down. The mice with the anxious personality spent
an average of four and a half minutes slowly and carefully making their way off the platform.
The “extroverted” mice jumped down in seconds. Then, the scientists switched the
microbiota of the two types of mice and did the platform test again. The mice with the
extroverted personality, after receiving the microbes of the anxious mice, now took over
a minute to get off the platform. On the other hand, after getting the microbes from the
extroverted mice, the “anxious” mice got off of the platform a whole minute quicker.
What this group showed was that in these mice, behavior and levels of anxiety were dependent
on which microbes were living in their gut. One other thing: remember BDNF, the protein
that we should like to have more of for better brain function? Well, the microbiota switch
that made the “anxious” mice more “confident” also increased their levels of BDNF. The change
in microbiota not only made observable changes in behavior, but in brain chemistry as well. In fact, there’s all kinds of chemistry
going on in the gut that can affect the brain. There’s even research identifying which
specific microbes produce which neurotransmitters. For example it’s estimated that 90% of our
serotonin is produced in the gut, and it’s been found that some of this serotonin is
produced by these four microbes. These two microbes produce gamma-Aminobutyric
acid or “GABA” – our chief inhibitory neurotransmitter which has relaxing and anti-anxiety
effects. And these two (Bacillus and Serratia) produce
our motivation neurotransmitter, dopamine. [R] So we basically have this huge mass of little
drug factories sitting in our gut pumping out different substances that affect our brain.
In fact the gut and its microbes appears to affect the brain so much that preclinical
research in rodents suggested that certain probiotics have antidepressant and anti-anxiety
effects. Probiotics are basically substances you can take orally to stimulate the growth
of microbes. One study even found that a Bifidobacterium infantis probiotic had anti-depressive effects
on par with that of the anti-depressant drug citalopram. I used to think that the only benefit of fiber
was that it helped you poop. However, considering dietary fiber isn’t food for us but for
our microbes, a diet rich in fiber from a variety of sources should also be good for
our mental health. This information about the gut microbiome
makes you start to wonder how many mental afflictions could be traced back to disruptions
in gut health from, for example, diets rich in fiberless processed foods and refined carbohydrates,
or from the unmitigated use of antibiotics. Antibiotics can be a life saver when absolutely
necessary as we saw at the start of the video, but the most commonly prescribed antibiotic
– a wide-spectrum antibiotic doesn’t just kill the offending bacteria, but all kinds
of other bacteria get caught in the crossfire. This is like poisoning your cat along with
a bunch of cockroaches you’re trying to kill. In the United States alone, tens of millions
of people are prescribed antibiotics for minor afflictions. 60 to 80 percent of children
taken to the doctor complaining of bad sore throats or ear pain will walk out with an
antibiotic. It’s estimated that people will take 30 courses of antibiotics by the age
of 40. But, the highest prescription rate was for children under the age of two with
1,365 courses per 1000 babies. So, could all these antibiotics affect the
young gut microbiome and the brain development of these children? A 2012 paper by Dr. Derrick MacFabe describes
what happens when rats are injected with something called Propionic Acid or PPA. The PPA injection
provoked peculiar changes in the rats’ brains like neuroinflammation, increased oxidative
stress, and glutathione depletion.The rats also displayed abnormal movements, repetitive
interests, cognitive deficits, and impaired social interactions. Basically, the results
of this injection were very similar to autism spectrum disorders. And, PPA is a fermentation
product of bacteria, namely Desulfovibrio, Bacteroidetes and Clostridia. It was found
that patients with autism have many more species of the clostridium bacteria and have high
levels of PPA in their feces. It’s estimated that in one third of patients,
autism doesn’t show up until around 18 to 24 months. Several reports from parents say
that their children were developing normally until they received antibiotics for upper
respiratory or ear infections. According to Dr. Sydney Finegold, antibiotics wipe out
or suppress several organisms in the gut, but Clostridia is one of the ones that persists. A CBC program titled “The Autism Enigma”
features Ellen Bolte who explains how her son Andrew’s behavior changed drastically
after 6 courses of antibiotics over a 2 to 3 ½ month period for an ear infection. After
this, he was diagnosed with severe autism. Digging into the research, Ellen came across
information about the Clostridia bacteria, so she started searching for a doctor who
would be willing to try an antibiotic called “vancomycin” on Andrew. Vancomycin is
specifically designed to target the Clostridia bacteria. After she finally found a doctor
who agreed to test her theory, they tried the antibiotic and it had impressive effects.
“The results were astounding. Within a matter of just a few weeks, he became calm. He was
aware of his environment… he’s putting puzzles together…” The antibiotic brought out improvements
in Andrew that were transient but drastic. This case lead to a pilot study with Dr. Finegold
and a Dr. R Sandler who found that out of 10 autistic children treated with vancomycin,
8 of them had again transient but significant improvements. Now, jumping to conclusions about the cause
autism has not been… helpful in the past… but this idea that autism could be the result
of a disturbed gut is gathering more and more data. A disturbed gut ecosystem would also
explain the very common gastrointestinal issues autistic children suffer. Some estimates say
that as high as 70% of children with autism spectrum disorders also have gastrointestinal
issues. Autism is just one of the disorders that can
be linked to a disruption in gut health, and research on the gut microbiome is growing
quickly. About 3600 related articles on this topic were published between 2010 and 2015.
At this point, saying the gut microbiome is important to health is an understatement.
Dr. Martin Blaser says that “losing your entire microbiome outright would be nearly
as bad as losing your kidneys or liver.” Unlike the kidneys or liver however, you can
change the makeup of your microbiome with what you put into your mouth. I guess Hippocrates knew what he was talking
about when he said “All disease begins in the gut,” and “Let food be thy medicine.” This video was brought to you by Squarespace.
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My friend the toadstool, he just left the
party, ‘cause there wasn’t mushroom! And it’s too bad, ‘cause he was a real
fun-guy. Ok…ahh… in addition to being fun guys, fungi
are incredible organisms. They make up their own kingdom in the eukaryotic
domain of the tree of life, separate from animals and plants. This kingdom includes everything from microscopic
organisms like yeast and mold, to those familiar dome-shaped mushrooms you can find at the
grocery store… or in Super Mario. And since there are so many different kinds of
fungi, it’s no wonder that some of them have pretty crazy talents. [Music Playing] First, we have a classic fungus: the mushroom.
The magic mushroom, to be precise. These mushrooms contain the chemical compounds
psilocybin and psilocin In the human body, the psilocybin gets broken
down into psilocin, which is the active form of the hallucinogenic drug. The chemical structure of psilocin is similar
to the neurotransmitter serotonin, which normally sends signals between brain cells to regulate
things like mood, memory, and sleep. So, psilocin tricks the brain into activating
those serotonin receptors. And this can cause hallucinogenic effects,
like changing thought patterns and mood, visual distortions, and even a sense of euphoria. There’s some sketchy anthropological evidence
that magic mushrooms could have been used in religious ceremonies by different cultures, but those theories are controversial among historians. The mushrooms hit the U.S. cultural scene
in the 1950s, though, after a mycologist, a scientist who studies mushrooms, brought
the practice back after a trip to Mexico. By the 1970s, these mushrooms were illegal
in the US, after being widely used as a recreational drug. But they may be making a comeback for another
purpose: psychotherapy. With permission from the U.S. government,
certain researchers are carefully conducting studies to explore the benefits of small doses
of psilocybin to treat conditions like post-traumatic stress disorder and chronic depression. Some mind-altering fungi have more dangerous
side effects. In fact, one of the most famously horrifying
events in early American history may have a fungal infection to blame. Ergot fungi are members of the genus
Claviceps. And the most well-known variety is Claviceps
purpurea, which grows on rye and other grains. The fungus produces some toxic nitrogen-containing
compounds called alkaloids. In particular, it creates lysergic acid.
Which might sound familiar because it’s used to synthesize the psychedelic drug lysergic
acid diethylamide, better known as LSD. Lysergic acid alone can lead to mania and
psychosis, while other alkaloids in ergot fungus can cause seizures and spasms, headaches,
nausea, crawling skin, and vomiting. As it turns out, many of these fun symptoms are very similar to the effects of the so-called “bewitchment” recorded in the Salem Witch
Trials in 1692, where both women and men were accused of witchcraft, tried in court,
and even executed. At the time, rye was a staple in the diets
of Salem residents. And warm, humid weather the previous year
would have made a prime breeding ground for ergot fungus. Ergot poisoning probably can’t account for
all of the hysteria surrounding the witch trials, but it all could have started with
some fungus in their food. Pop culture is full of zombies, but it’s
a relief to know that the apocalypse is not upon us… yet. The same can not be said for camponotini
ants, who face a unique threat to their colonies: zombie ants! A particular type of fungus called Ophiocordyceps
unilateralis can take control of the ants it infects. The infected ants show extremely specific behavior, they travel down to a lower level in the forest where the air is just humid and cool
enough, and find a leaf on the north side of a plant about 25 centimeters above the
ground. Then, they clamp down onto the underside of
the leaf and die. After a few days in these ideal conditions,
thin stalks of fungus sprout from the ant’s head so that spores can be released, in the hope of infecting more ants and continuing the cycle. Scientists aren’t sure yet how this fungus
can so carefully control the ant’s behavior, but this isn’t the only parasite to have
evolved mind-controlling abilities. One of the great medical achievements of the 20th century was the discovery and isolation of the antibiotic penicillin. Without a reliable way to kill off the bacteria
causing an infection, something a simple as a scratch could turn out deadly. But, in the late 1920s, bacteriologist
Alexander Fleming, noticed that Penicillium notatum mold had contaminated one of his petri dishes and killed all of the bacteria it touched. That was because the Penicillium mold produced
a bacteria-killing chemical that Fleming eventually called penicillin. It attacks the enzymes that build the bacterial
cell walls, so the walls fall apart, and the bacterium dies. Researchers at Oxford University then worked
on mass-producing, purifying, and testing the antibiotic, which went on to save thousands
of soldiers from death by infection in World War II. Pretty incredible stuff for a bread mold! And, penicillium isn’t the only life-saving
fungus out there. Tolypocladium inflatum seems pretty boring at first glance. It lives in Norwegian soil and can infect
beetle larvae. But this fungus produces a compound called cyclosporin, which is really good at suppressing our immune systems. It sounds dangerous and bad when you put it that way, but cyclosporin is an important drug that keeps organ implants from being
rejected. Normally, the patient’s immune system would
see the implanted organ as an intruder and attack it using the body’s first line of
defense: the T-cells. But cyclosporin inhibits those cells, preventing
the attack, and protecting the new organ as the patient’s body adjusts. And continued low doses of this drug can keep
organ transplant recipients healthy for years. When you think fungi, you usually think…like, pretty small. Like, cute-little-mushrooms-in-the-forest small.
Or even microscopic-mold small. But it turns out that some fungi can get huge. In fact, the largest living organism on the
planet is a massive honey fungus, of the Armillaria solidipes variety. This honey fungus has genetically identical
cells that can communicate and coordinate with each other, which, by one biological
definition, makes it a single organism. It’s estimated to cover around 9.6 square
kilometers in Oregon, and may be thousands of years old. But it’s not obvious how big this thing is. Clumps of mushrooms will appear above the surface
of the soil to release spores, but most of the fungus exists underground. Root-like rhizomorphs search for new host
trees to infect, while a network of thin, tube-like filaments called mycelia absorb
nutrients from the soil to keep this fungus growing. Not many people notice Pilobolus
fungus, since it’s a couple centimeters tall and mostly grows on… manure. But this unglamorous fungus has a secret superpower. During its reproductive phase, it forms thin,
pale stalks, called sporangiophores, with bulbs at the end containing spores, called
the sporangium. Pressure builds in the bulb until it eventually
bursts, sending the spores shooting around two meters away into nearby grass, so cows can eat it and the circle of life can continue. Now, that might not sound very impressive,
but these spores are accelerated at around 20,000 g’s. To put it in perspective, the shot coming out of a shotgun probably maxed out at around 15,000 g’s. That is a lot of acceleration for a tiny fungus. Death Cap and Destroying Angel mushrooms are
easily mistaken for edible fungi. But, as you might’ve guessed from their
names, they contain some of the most deadly substances known to humans. Other dangerous fungi include the deadly webcap
and the fool’s webcap. Both webcaps are part of the Cortinarius
genus and look like common brown mushrooms that you can eat. But, they produce a toxin called orellanine, which can cause kidney failure, and sometimes death. Plus, it can take anywhere from two days to
three weeks for symptoms to show up, so poisoning can be really hard to diagnose. The Japanese fungus Podostroma cornu-damae has some particularly nasty effects as well. Eating this rare red fungus causes altered
perception, severe upset stomach, hair loss, peeling skin, and even shrinking of the cerebellum, the part of your brain responsible for movement and coordination. The fungus is so rare that not many cases
of poisoning have been reported, but most of the known cases have been fatal. So it’s probably not a great idea to go
around eating random wild mushrooms. To make cheese, milk has to be soured, causing the solids, or, the curds, to separate from the liquids, or, the whey. The curds are then mixed with some other stuff, before they’re processed into the final cheese product. In the case of some popular cheeses like Roquefort, a type of blue cheese, this includes deliberately contaminating the curds with
fungus! Penicillium roqueforti is another
bread mold, from the same Penicillium genus as the life-saving antibiotic. The mold produces enzymes that break down
proteins in the cheese curds, helping create a distinctive smooth texture and strong, tangy
taste. Legend has it that people would place loaves
of bread in the caves surrounding the Roquefort region of France, hence the name. The loaves would grow moldy and dry out, be
pulverized into a powder, and then added to the cheese, giving it that delightful blue
veiny appearance. Nowadays, Penicillium roqueforti can be purchased
in stores, so you can make your own fungus-filled blue cheese at home! Humans have been consuming alcoholic beverages
for at least 7,000 years. And it turns out making beer wouldn’t be
possible without the help of a fungal friend named yeast. Specifically, a yeast called Saccharomyces cerevisiae. See, in beer brewing, grains are cooked in
water to form a mash. And then, they’re boiled to break all the starches down into simpler
sugars, and flavoring agents like hops are added. Once this mixture cools down, the yeast is
added, and that’s when the magic happens: Yeast eat all those sugars in the mash to
give them energy to reproduce, in a chemical process called fermentation. And they also generate a lot of waste, in
this case, carbon dioxide and ethanol. The carbon dioxide is what gives the beer
its characteristic fizz, while the ethanol is what gives humans their characteristic buzz. Thank you for watching this episode of SciShow,
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